Today, automotive inflatable safety systems are becoming commonplace for reducing the incidence of serious injuries to automobile occupants in automobile accidents. These automotive inflatable safety systems generally comprise an appropriate detector, an inflator assembly and an air/safety bag. When triggered by the detector, such as the result of an automobile collision, the inflator assembly provides gases to inflate the air/safety bag to protect the occupants of the automobile from interior components of the automobile.
A considerable amount of effort has been expended in designing inflator assemblies, or simply "inflators" for use in automotive inflatable safety systems. Inflators have been designed which use stored gases, gas generating propellants and a combination of stored gases and gas generating propellants for inflating the air/safety bag. Inflators using pyrotechnic propellants allow for the use of inflators that are compact in size and weigh less than other types of inflators, such as stored gas inflators which contain heavy and bulky gas storage tanks. Due to weight and space constraints imposed by the automobile structure, most modern automotive inflatable safety systems utilize a pyrotechnic gas generating propellant for inflating the air/safety bag. Inflators utilizing only gas generating, pyrotechnic propellants ("pure pyrotechnic inflators") and inflators which utilize both stored gases and gas generating, pyrotechnic propellants ("hybrid inflators") are at present, commonly in use.
Known pyrotechnic propellants used in automotive inflatable safety systems, such as those based upon azides, nitrotriazoles and tetrazoles, have several drawbacks. In some instances, the propellant compositions can produce combustion gases, such as carbon monoxide, which can be dangerous to the occupants of an automobile if present in large quantities. Most known pyrotechnic propellants used in inflators produce hot gases and airborne liquid or solid particulate matter which, unless filtered from the produced gas, could destroy or puncture the air/safety bag, potentially harming occupants of the automobile. The addition of complex mechanisms for filtering the generated gases undesirably increases the intricacy of the inflator design and leads to increased production costs. In addition, most pyrotechnic propellants currently used in inflators produce smoke, which, even if physically harmless, may have negative psychological effects upon automobile occupants who have experienced an accident.
Based on the foregoing, it is evident that in general, it is both useful and desirable to provide pyrotechnic propellants which would allow use of inflator assemblies having reduced weight and size than inflators commonly in use. It would be further desirable to provide pyrotechnic propellants which generate substantially little to no airborne particulate matter upon combustion, thereby reducing filtering requirements for the produced gases and allowing for the use of inflators having simplified designs. Moreover, it would be desirable to provide pyrotechnic propellants for use in an automotive inflatable safety system which produce substantially little to no smoke or toxic gases.